Automatic hammer



Oct. 7, 1930.

Filed April 9, 1928 Patented Get. 7, 1930 PATENT entice ROY J. CHAMPAY NE, OF ROCKFORD, ILLINOIS AUTOMATIC HAMMER Application filed April 9, 1928.

This invention relates to automatic hammers and is particularly concerned with a hammer which may be driven by an electric motor mounted integrally with the hammer or by a motor which may be in some suitable manner connected temporarily therewith. It will be evident that this hammer will have many uses and that one of them would be found in the work of re- 19 moving dents from automobile fenders.

This invention provides a construction in whicha reciprocating striking member is thrust forwardly in the striking movement by the action of a spring and is retracted by the lifting action ofa cam. Inasmuch as the cam does not propel the striker in the striking movement the cam need not be subjected to great wear or shock. In'this invention the cam retracts the striker after the striking blow and places it in position to be driven forward again bythe spring.

The forward movement of the striking memher is checked or limited so that it does not at that instant bear against any surface of the cam. This enables the cam to rot-ate on highly efiicient ball'or roller bearings which will not be damaged by the operation of the hammer.

One of the objects of the invention is to provide an automatic hammer which is. retracted by a cam and propelled in the striking blow ,by a spring.

Another object of this invention is to provide a hammer retracted by a cam 'and so constructed'that an annular cam'of relatively large diameter may be used in order that the retractile movement of the striker against the spring may be gradual thus favoring the use of a small arnount of motive power for rotating the cam. I

Anotherobject of this invention is to provide an automatic hammer havingfij a striking member retracted by a cam and propelled by a spring whose tension may be easily and quickly adjusted by means accessible from, the exterior. of the case without removal of parts.

Another object of this invention is to provide an automatic hammer. having a striker propelled by a spring and retracted by a cam revolves.

the cam. It is not material to this invention Serial No. 268,780.

cam and having means for preventing the cam from receiving any impact from the. striking blow.

Another object of this invention is to provide an automatic hammer propelled by a spring and retracted by a cam having a relatively long and gradual sloping cam surface and adapted to be propelled by a motor all of which may be mounted in a compact case. i

Other objects, advantages and capabilities are inherently possessed by this invention and. will later appear.

Referring now to the drawing,

Fig. 1 is a central sectional view of the o5 hammer showing the cam and case in section and the striker in elevation, with the motor indicated diagrammatically.

Fig. 2 is a side elevation of the cam itself removed from the hammer. 1

Fig. 3 is a partial sectional view of a modified form of a hammer showing a cam follower attached to the post about which the Fig. 4' is a sectional view of the modified form of hammer on the line 44 of Fig. 3. Fig. 5 is a fragmentary cross-section taken substantially on the line 5--5 of Fig. 1.

In the preferred form shown in Fig. 1, the lower half 1 of the hammer casing has mountv ed in it a post 2 secured therein by a in 3.

Underneath the head 4 of the post is re tained an annular cam 5, which is provided with aworking face 6 which is adapted to bear against the cam follower 7. The cam is provided with internally cut gears 8 into which is meshed a pinion'9 on the motor 11.

A ball thrust bearing generally indicated as 12 absorbs the thrust on the underside of whether ball bearings or roller bearings be used inasmuch as several types of bearings would function satisfactorily. A striking member 13 extends through the upper half 14 and the lower half 1 of the casing and is. retracted within the casing by the liftin force of thecam against the cam follower and is propelled outwardly from the casing by the compression spring 15. A collar 16 is screwed into 'the lower end of the casing blow.

, ing member.

and carries on its inner surface av washer 17 made of some suitable material such as rubber which will limit the forward movement of the striking member without damage to the device. Obviously this collar 16 is adjustable and by screwing it into the casing the outward movement of the striking member is limited at a point where the cam follower will fail to touch the lowermost portion of the cam. Reference to Fig. 1 and Fig. 2 will indicate that when the roller drops ofi the high point of the cam the spring will thrust the striker outwardly until the collar and washer 16 and 17 stop it. There will therefore be no hammering of the cam follower upon the cam during the striking movement.

The inner end of the compression spring seats against the end of the enlarged portion of the striking member and the outer end of the compression spring 15 rests against the adjustable collar 18. By screwing this collar inwardly or outwardly the tension of the spring may be increased or decreased respectively, thus varying the force of the striking The striking member is prevented from rotating by the cam 5 which fits in the arcuate undercut 19 in said member, as shown in Fig. 5.

It will be observed that the cam follower 7 which rotates about a pin 21 is positioned along the center line of the striking member and cooperates with the cam so that the thrust of the cam is exerted centrally on the strik- There will therefore be no appreciable side thrust on this striker and hence none of the disadvantages arising from side thrust.

A handle 22 provides a convenient grip and houses a switch 23 having a convenient trigger 24.

In the modification, the striking member 25 is not provided with as large a recess as is shown in the preferred form, as the cam 26 does not extend within the lateral sides of the striker. A cam follower 27 rotates on an arm 28, one end of which arm is pivoted by the pin 29 to the top of the cam retaining post 31. The other end of the arm 28 is provided with a knuckle 32 which fits into the recess 33 and forces the striking member back into the case.

In the modified form of hammer the spring and motor and other parts not mentioned here would be the same as in the preferred form and the striking member is prevented from rotating by means of the knuckle 32.

The operation of the device is as follows:

The motor pinion 9 meshes with the internal gear 8 and causes the cam to rotate. The

cam follower 7 rides gradually up the inclined face of the cam until it passes over the highest point 35 as shown in Fig. 2. By this time the spring 15 has been compressed very considerably and as the follower drops ed the high point of the cam the spring thrusts the striking member 13 upwardly. The collar 16 and washer 17 limit the movement of the striker so that the follower does not strike the lowermost portion 36 of the cam.

As the stroke of the striking member outside of the casing will preferably be short to prevent excessive rebound, it will be found convenient to adjust the collar 16 so that not only will the cam be saved from the impact of the striker but also so that the striker may not be propelled too far outside of the casing.

The construction of the preferred form makes possible the use of a relatively large lifting cam neatly disposed and protected within a comparatively small and compact casing. The annular working face of the cam' Such a long slope enables a small motor to gradually lift the striker a considerable distance against the opposing force of a strong spring. Thus unusually greater force and momentum of the striker may be obtained in a small, compact hammerl It should be understood that the drawings and specifications disclose embodiments of the invention which have been selected for purposes of illustration only, hence it should be borne in mind that the invention comprehends other constructions which may differ considerably from this disclosure.

Having shown and described my invention I claim:

1. In an automatic hammer, the combination ofa reciprocahle striking member, resilient means for actuating said member in one direction for striking, an annular cam for retracting the member in the opposite direction, the center line of the member and the axis of the cam being out of coincidence, said member being cut-out between its ends, the working face of the cam being adapted to extend into the cut-out portion of said member to intersect the longitudinal center line of the member, a cam follower carried by said member adapted to be engaged by the cam face, and means for rotating the cam.

2. In an automatic hammer, the combination of a reciprocable striking member, resilient means for actuating said member in one direction for striking, an annular cam for re tracting the member in the opposite direction, the member being cut out intermediate its ends to permit the annular working face of the cam to revolve across its center line, means cooperating with the working face of the cam'coincidental with the center line of said member for retracting said member, and

means acting on the outer circumferential portion of the cam for rotating the earn,

3. in an automatic hammer, the combination of a reeiprocable striking member, resilient means for actuating said member in one direction for striking, an annular cam for retracting the member in the opposite direction, the member having a recess intermediate its ends, the cam being rotatable about an axis out of coincidence with the center line of said member and having its annular Working face extending into said recess, means cooperating with the part of the cam revolving through said recessto retract said member, and means for revolving the cam.

4:. In an automatic hammer, the combination of a reciprocable striking member, resilient means for actuating said. member in one direction for striking, an anrular cam for retracting the member in the opposite direction, means acting upon said member intermediate its ends and cooperating with the cam to retract said member, the striking end of the member being at one side of the cam and the resilient means being located at the other side of the cam, means accessible from the outside of the hammer for adjusting the tension of said resilient means to vary the force of the striking movement of said memher, and means for rotating the cam.

53. In an automatic hammer, the combination of a reciprocable striking member, resilient means for actuatingsaid member in one direction for striking, an annular cam for retracting the member in the opposite direction, the cam being rotatable about an axis parallel to the center line of said member and separated therefrom a substantial distance and having an annular Working face for retracting said member gradually, a follower cooperating with'the cam face for retracting said member, and means for exerting rotative force on said cam near its circumferential portions.

In Witness of the foregoing I affix my signature.

ROY J. CHAMPAYNE. 

